The invention concerns a half-bridge circuit, especially for connection of an electric motor in a vehicle.
It is known to control a DC motor with a so-called bridge circuit that permits operation of the DC motor in both directions of rotation. For this purpose, the known bridge circuit has four circuit elements, for example, in the form of power transistors, each two circuit elements being connected in series between ground and the supply voltage and forming a so-called half-bridge. The DC motor is connected with its two terminals to the connection points of the two series-connected circuit elements of the two half-bridges. In this manner, the DC motor can be acted upon by appropriate control of the four circuit elements with a voltage of the desired polarity, so that operation of the DC motor in both directions of rotation is possible. For this purpose, for example, only the high side circuit element is switched in the one half-bridge, whereas only the low side circuit element is switched in the other half-bridge. For pole reversal, the other circuit element is then switched in both half-bridges. It is then important that only one of the two circuit elements is switched in each half-bridge, whereas the other circuit element is blocked, in order to prevent a short-circuit along the half-bridge.
A problem here is the design-related parasitic inductance between the buffer capacitor and the high side or low side circuit element.
A shortcoming in the design of such a bridge circuit with discrete components is also the relatively large space requirements, because of the necessary bending geometries and line tensions, so that the spacing between the low side circuit element and the high side circuit element is relatively large, which leads to a relatively high-inductance connection to the intermediate circuits.